Fuel injection apparatus for internal combustion engines

ABSTRACT

In a fuel injection apparatus the setting of the fuel metering valve in response to the deflection of an air sensor in the air intake tube is effected by an electric follower regulator circuit to which there is applied a setting magnitude characterizing the deflection of the air sensor. Output signals of the circuit are applied to an electromagnetic setting device operatively connected to the fuel metering valve.

i United States Patent 1191 Knapp et al.

[ FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES [75] Inventors: Heinrich Knapp,

Leonberg-Silberberg; Reinhard Schwartz, Stuttgart-Sillenbuch, both of Germany [73] Assignee: Robert Bosch, GmbH, Stuttgart,

Germany [22] Filed: Aug. 13, 1973 [21] Appl. No.: 387,816

Related US. Application Data [63] Continuation of Ser. No. 190,002.01, 18, 1971.

[30] Foreign Application Priority Data Oct. 21, 1970 Germany 2051584 [52] US. Cl. 123/32 EA; 123/139 AW [51] Int. Cl. F02M 39/00; F028 3/00 [58] Field of Search..... 123/32 EA, 119 R, 139 AW [56] References Cited UNITED STATES PATENTS Goodridge 123 32 EA 1 Nov. 4, 1975 3,628,515 12/1971 Knapp 123/139 AW 3,630,177 12/1971 Engel 123/32 EA 3,648,155 3/1972 Soehner... 123/32 EA 3,680,535 8/1972 Eckert 123/139 AW 3,683,870 8/1972 Jackson 123/32 EA Primary ExaminerCharles J. Myhre Assistant ExaminerRonald B. Cox Attorney, Agent, or Firm-Edwin E. Greigg [57] ABSTRACT In a fuel injection apparatus the setting of the fuel metering valve in response to the deflection of an air sensor in the air intake tube is effected by an electric follower regulator circuit towhich there is applied a setting magnitude characterizing the deflection of. the air sensor. Output signals of the circuit are applied to an electromagnetic setting device operatively connected to the fuel metering valve,

15 Claims, 2 Drawing Figures Sheet 1 of 2 U.S. Patent Nov. 4, 1975 Sheet 2 of 2 US. Patent Nov. 4, 1975 FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES This is a continuation of application Ser. No. 190,002, filed Oct. 18, 1971.

BACKGROUND OF THE INVENTION This invention relates to a fuel injection apparatus particularly for externally ignited internal combustion engines and is of the type that effects a continuous fuel injection in the suction tube of the engine and has, in a series arrangement in the air intake tube of the en gine, an air sensor and an arbitrarily operated butterfly valve. The air sensor which is displaced against a constant return force by the air flow to an extent proportionate to the throughgoing air quantities, controls a fuel metering valve member through a setting device.

In a fuel injection apparatus of the aforenoted type, such as disclosed in US. Pat. No. 3,613,650, issued on Oct. 19, 1971 to Gerhard Stumpp and Klaus-Jurgen Peters, the setting device is formed of a relatively complex lever assembly which, by virtue of its mechanical nature, must be disposed in the vicinity of the air sensor. It is, however, a desideratum to keep the structural volume of the air intake tube as small as possible in the range of the air sensor. Therefore, it is advantageous to dispose the regulator and correcting components at another location of the vehicle, if possible. It is further a disadvantage of a mechanical setting device that is sensitive to the vibratory motions caused by the engine.

OBJECT AND SUMMARY OF THE INVENTION It is an object of the invention to provide an im proved fuel injection apparatus in which the aforenoted disadvantages are eliminated.

Briefly stated, according to the invention the setting device, which is preferably an electromagnetic setting assembly, is actuated by means of a follower regulator circuit containing electrical and mechanical components. The actuating signals applied to said circuit are generated by and are proportionate to the excursion of the air sensor.

The invention will be better understood, as well as further objects and advantages become more apparent, from the ensuing detailed specification of two exemplary embodiments taken in conjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a schematic view of a fuel injection apparatus incorporating a first embodiment of the invention and FIG. 2 is a schematic view of a fuel injection apparatus incorporating a second embodiment of the invention.

I DESCRIPTION OF THE EMBODIMENTS Turning now to FIG. 1, in a suction or air intake tube 1 of an internal combustion engine (not shown) there are arranged an air sensor 2 and, downstream thereof, an arbitrarily operable butterfly valve 3. The sensor 2 is formed as a plate which is affixed to a swinger lever 4 pivotally held at 5 and which is adapted to be deflected by the air stream against the force of a spring 6. The latter has a very flat spring characteristic so that the force of the spring is only very slightly different for the different angular positions of the sensor 2. In this manner it is ensured that the sensor 2 is displaced proa motion of the air sensor 2 into a measured value of pro portionately to the air quantities which flow through the intake tube 1 and which are determined by the position of the butterfly valve 3. The magnitude of the excursion of the sensor 2 serves as a command variable for a regulator circuit which controls a setting device operatively connected to a fuel metering valve 7 and to be described hereinafter. The fuel metering valve 7 is supplied with fuel through a fuel line 8 by means of a continuously delivering fuel pump (not shown) which forces the fuel metered by the metering valve 7 through conduits 9 to the suction tube into which the fuel is injected in the vicinity of each engine intake valve.

The follower regulator circuit is formed as an electric regulator circuit in which inductive voltage dividers 11 and 12 serve as signal transmitters. With the pivotal lever 4 of the air sensor 2 there is mechanically connected the signal transmitter 11 which transforms the portionate magnitude. Also, the position of the setting device to be described later is transformed by means of the signal transmitter 12 into a proportionate measured value serving as a regulating magnitude. The signal transmitters 11 and 12 form part of an electric bridge circuit, the voltage source of which is an oscillator 13. The measured values representing the regulating magnitude and the command magnitude are compared and the difference between the two values is amplified in a discriminator amplifier 14. The output of the latter is connected with the setting device so that by virtue of the follower regulator circuit, the setting device is caused to follow the motion of the air sensor 2 and assume a corresponding position. The branches of the bridge circuit contain additional transducers 15 which sense engine variables or variables relating to the engine environment and which, as regulating magnitudes, affect the output magnitude of the discriminator amplifier 14. Thus, the signal transmitter 15 may be, for example, a temperature-dependent resistance which senses the engine temperature or the intake air temperature and brings about an additive or multiplicative enrichment of the fuel-air mixture. It is noted that the electric output signals of the aforedescribed regulator circuit may also be used, for example, to control the ignition timing.

An air sensor of the type under consideration may overshoot during acceleration or may vibrate in response to suction pulses generated by the engine. In order to avoid such occurrences, the output magnitude of the discriminator amplifier 14 is used to effect an electromagnetic damping. In case the air sensor 2 overshoots, there is generated a current pulse which, amplifled by the discriminator amplifier 14, is applied to a frequency-dependent passive circuit which may be formed by an RC component 17. The output magnitude of the latter is amplified by an amplifier 18 and is applied to an electromagnet 19 which serves as a braking magnet. In the embodiment illustrated in FIG. 1, the braking magnet 19 is of the plunger-type which, in case of sufficiently strong air flow, works against the setting motion of the air sensor 2 as a negative feedback.

In the embodiment according to FIG. 1, the setting device is formed of a rotary magnet 20 to which there is coupled, for unison rotation, an axially displaceable three-dimensional cam 21. The axial displacement of the three-dimensional cam 21 is effected by means of a piston 22 which is actuated as a function of the pres+ sure which prevails in the intake air tube 1 downstream of the butterfly valve and which is transmitted through a conduit 23. The three-dimensional cam 21 is operatively connected with'a setting member 24 of the fuel metering'valve 7. By utilizing the pressure prevailing in the suction tube, the setting of the three-dimensional cam 21 is also a function of load, since the pressure in the air intake tube is determined by the rpm and by the position of the butterfly valve 3. Since the sensing of the 'th roughgoing air quantities in the. suction tube 1 as well as the electric transmission of signals representing the deflection of the air sensor proceed in a substantially linear manner, the three-dimensional cam 21 may have a near linear slope in the direction of the setting motion, insofar as the fuel metering valve also operates linearly. Such three-dimensional cam is simple to manufacture.

Turning now to FIG. 2, in the second embodiment shown therein, the setting device is formed of a plunger-type magnet 25, the armature 25a of which is integral with the fuel quantity setting member 24a of the fuel meterin g valve 7a. In order to permit a direct utilization of the engine load as an actual value, between the signal transmitter 12 and the discriminator amplifier 14 there is connected a further signal transmitter 26 which functions as a correcting regulator member and. which transforms the position of the butterfly valve 3 into a measured value of proportionate magnitude. In the embodiment according to FIG. 2, for the brak- .ing of the air sensor 2 there serves a braking magnet 27,

the armature 27a of which presses an appropriately flattened portion 28a of a rod 28 connected with the pivotal lever 4 to a brake shoe-type block 29.

What is claimed is:

1. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) anair sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities flowing through said airintake tube, (b) a spring connected to said air sensor for exerting thereon a substantially constant return force opposing the deflection of said air sensor, (c) a fuel metering valve for determining the fuel quantities to be injected into-said internal combustion engine, (d) a setting device operatively connected to said air sensor and to said fuel metering valve for controlling the latter as a function of the extent the air sensor is deflected, the improvement comprising an electric follower regulator circuit including A. means for applying a voltage to said regulator circuit, Y

B. afirst signal transmitter connected to said air sensor for applying to' said regulator circuit a signal representing the extent of deflection of said air sensor,

C(a second signal transmitter connected to said setting device for applying to said regulator circuit a signal representing the position of said setting device,

D. means for forming a signal representing the difference between the two signals defined in (B) and (C) and v E. means for applying the signal defined in (D) to said setting device.

2. An improvement as defined in claim 1, said regulator circuit including at least one additional signal transmitter for applying to said regulator circuit a signal representing a further engine variable in addition to the extent of deflection of said air sensor.

3. An improvement as defined in claim 1, said signal transmitters being formed as inductive voltage dividers and said means for applying a voltage to said regulator circuit being formed as an oscillator.

4. An improvement as defined in claim 3, said regulator circuit including a discriminator amplifier constituting the means defined in (D) and amplifying said signal defined in (D) for the actuation of said setting device.

5. An improvement as defined in claim4, including A. an RC member forming a frequency-dependent passive circuit component connected to the output of said discriminator amplifier,

B. an additional amplifier connected to the output of said RC member and C. electromagnetic damping means connected to the output of said additional amplifier and to said air sensor to dampen the motions of the latter.

6. An improvement as defined in claim 5, said electromagnetic damping means being formed as a negative feedback or counter-coupled magnet.

7. An improvement as defined in claim 5, said electromagnetic damping means being formed as a plungertype magnet, said improvement further including friction brake means connected with said air sensor and exposed to the force of said plunger-type magnet.

8. An improvement as defined in claim 5, including a temperature-dependent resistance forming part of said regulator circuit to affect the output thereof as a function of the engine temperature.

9. An improvement as defined in claim 8, including an additional temperature-dependent resistance forming part of said regulator circuit to affect the output thereof as a function of the intake air temperature.

10. An improvement as defined in claim 8, wherein said temperature-dependent resistance is connected in series with said first signal transmitter.

11. An improvement as defined in claim 1, including A. a correcting control member forming part of said regulator circuit and B. means connecting said butterfly valve with said correcting control member for causing the latter to generate correcting signals as a function of the position of said butterfly valve.

12. An improvement as defined in claim 11, wherein said correcting control member is connected in series with said second signal transmitter.

13. An improvement as defined in claim 11, wherein said correcting control member is formed as an inductive voltage divider.

14. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) an air sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities connected to said air sensor and to said fuel metering valve for controlling the latter as a function of the extent the air sensor is deflected, the improvement comprising an electric follower regulator circuit including A. mechanical circuit components,

B. a three-dimensional cam connected to said setting device to be moved thereby,

C. means for moving said three-dimensional cam in response to the air pressure prevailing in said air intake tube downstream of said butterfly valve and D. follower means connected to said threedimensional cam and fuel metering valve, said regulator circuit being connected to said air sensor and to said setting device, the measured values representing the extent of deflection of said air sensor being applied to said regulator circuit as a command variable therefor.

15. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) an air sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities flowing through said air intake tube, (b) a spring connected to said air sensor for exerting thereon a substantially constant return force opposing the deflection of said air sensor, (c) a continuously operating mechanically actuated fuel metering valve for determining the fuel quantities to be injected into said internal combustion engine, (d) a mechanical actuating member connected to said fuel metering valve, (e) a setting device operatively connected to said air sensor and to said fuel metering valve through said mechanical actuating member for controlling the latter and thereby the fuel metering valve as a function of the extent the air sensor is deflected, the improvement comprising a linearly actuated electric follower regulator circuit including mechanical circuit components, said regulator circuit being connected to said air sensor and to said setting device, the measured values representing the extent of deflection of said air sensor being applied to said regulator circuit as a command variable therefor, wherein said setting device includes an electromagnetic assembly actuated by output signals of said regulator circuit. 

1. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) an air sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities flowing through said air intake tube, (b) a spring connected to said air sensor for exerting thereon a substantially constant return force opposing the deflection of said air sensor, (c) a fuel metering valve for determining the fuel quantities to be injected into said internal combustion engine, (d) a setting device operatively connected to said air sensor and to said fuel metering valve for controlling the latter as a function of the extent the air sensor is deflected, the improvement comprising an electric follower regulator circuit including A. means for applying a voltage to said regulator circuit, B. a first signal transmitter connected to said air sensor for applying to said regulator circuit a signal representing the extent of deflection of said air sensor, C. a second signal transmitter connected to said setting device for applying to said regulator circuit a signal representing the position of said setting device, D. means for forming a signal representing the difference between the two signals defined in (B) and (C) and E. means for applying the signal defined in (D) to said setting device.
 2. An improvement as defined in claim 1, said regulator circuit including at least one additional signal transmitter for applying to said regulator circuit a signal representing a further engine variable in addition to the extent of deflection of said air sensor.
 3. An improvement as defined in claim 1, said signal transmitters being formed as inductive voltage dividers and said means for applying a voltage to said regulator circuit being formed as an oscillator.
 4. An improvement as defined in claim 3, said regulator circuit including a discriminator amplifier constituting the means defined in (D) and amplifying said signal defined in (D) for the actuation of said setting device.
 5. An improvement as defined in claim 4, including A. an RC member forming a frequency-dependent passive circuit component connected to the output of said discriminator amplifier, B. an additional amplifier connected to the output of said RC member and C. electromagnetic damping means connected to the output of said additional amplifier and to said air sensor to dampen the motions of the latter.
 6. An improvement as defined in claim 5, said electromagnetic damping means being formed as a negative feedback or counter-coupled magnet.
 7. An improvement as defined in claim 5, said electromagnetic damping means being formed as a plunger-type magnet, said improvement further including friction brake means connected with said air sensor and exposed to the force of said plunger-type magnet.
 8. An improvement as defined in claim 5, including a temperature-dependent resistance forming part of said regulator circuit to affect the output thereof as a function of the engine temperature.
 9. An improvement as defined in claim 8, including an additional temperature-dependent resistance forming part of said regulator circuit to affect the output thereof as a function of the intake air temperature.
 10. An improvement as defined in claim 8, wherein said temperature-dependent resistance is connected in series with said first signal transmitter.
 11. An improvement as defined in claim 1, including A. a correcting control member forming part of said regulator circuit and B. means connecting said butterfly valve with said correcting control member for causing the latter to generate correcting signals as a function of the position of said butterfly valve.
 12. An improvement as defined in claim 11, wherein said correcting control member is connected in series with said second signal transmitter.
 13. An improvement as defined in claim 11, wherein said correcting control member is formed as an inductive voltage divider.
 14. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) an air sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities flowing through said air intake tube, (b) a spring connected to said air sensor for exerting thereon a substantially constant return force opposing the deflection of said air sensor, (c) a fuel metering valve for determining the fuel quantities to be injected into said internal combustion engine, (d) a setting device operatively connected to said air sensor and to said fuel metering valve for controlling the latter as a function of the extent the air sensor is deflected, the improvement comprising an electric follower regulator circuit including A. mechanical circuit components, B. a three-dimensional cam connected to said setting device to be moved thereby, C. means for moving said three-dimensional cam in response to the air pressure prevailing in said air intake tube downstream of said butterfly valve and D. follower means connected to said three-dimensional cam and fuel metering valve, said regulator circuit being connected to said air sensor and to said setting device, the measured values representing the extent of deflection of said air sensor being applied to said regulator circuit as a command variable therefor.
 15. In a fuel injection apparatus associated with an internal combustion engine including an air intake tube and an arbitrarily displaceable butterfly valve disposed therein, said apparatus being of the type that includes (a) an air sensor disposed in said air intake tube upstream of said butterfly valve and adapted to be deflected to an extent proportionate to the air quantities flowing through said air intake tube, (b) a spring connected to said air sensor for exerting thereon a substantially constant return force opposing the deflection of said air sensor, (c) a continuously operating mechanically actuated fuel metering valve for determining the fuel quantities to be iNjected into said internal combustion engine, (d) a mechanical actuating member connected to said fuel metering valve, (e) a setting device operatively connected to said air sensor and to said fuel metering valve through said mechanical actuating member for controlling the latter and thereby the fuel metering valve as a function of the extent the air sensor is deflected, the improvement comprising a linearly actuated electric follower regulator circuit including mechanical circuit components, said regulator circuit being connected to said air sensor and to said setting device, the measured values representing the extent of deflection of said air sensor being applied to said regulator circuit as a command variable therefor, wherein said setting device includes an electromagnetic assembly actuated by output signals of said regulator circuit. 